1. Field of the Invention
The present invention relates to a voice coil type lens drive assembly for adjusting the focus of a lens by utilizing a repulsive magnetic force which a magnetic field created upon energization of a coil induces between the coil and a fixed magnet opposed to the coil.
2. Description of the Related Art
Heretofore, in connection with a voice coil type lens drive assembly for adjusting the focus of a lens by utilizing a repulsive magnetic force which a magnetic field created upon energization of a coil induces between the coil and a fixed magnet opposed to the coil, a method for winding the coil around a movable unit has been known as is disclosed, for example, in Patent Literature 1 (Japanese Registered Utility Model No. 3127325, see FIG. 7). According to this conventional method, as shown in FIG. 15, a coil 123d having been wound beforehand in a predetermined shape is mounted suitably around a coil base 243.
Although it is not that any special functional defect is found in the construction disclosed in Patent Literature 1, it is desired to remedy the following inconvenience. According to the construction in question, since the coil 123d having been wound beforehand in a predetermined shape is mounted suitably around the coil base 243, the mounting height of the coil 123d for the coil base 243 is not stable. Therefore, it is required that a predetermined gap for stabilizing operation be ensured between the coil 123d and a magnet M opposed to the coil 123d. In this case, for a margin taking into account variations in winding size of the coil 123d and stability of the mounting height, a somewhat wide gap is ensured.
As a result, the gap between the coil 123d and the magnet M becomes wider and hence the magnetic repulsive force induced upon energization cannot be utilized effectively, thus affording a lens drive assembly of poor efficiency. At the same time, an outline of the entire assembly becomes large and thus it becomes difficult to apply the above construction to a downsized lens drive assembly. Besides, there is a fear of wire breaking in a connection between plural coils 123d. This is unstable in point of handling.